FIG. 1 is a schematic diagram of an existing negative charge pump feedback circuit; a clock signal Clock is connected to an input terminal of an AND gate 102, an output terminal of the AND gate 102 is connected to an input terminal of a negative charge pump 101, an output terminal of the negative charge pump 101 outputs a negative voltage Vneg, and the feedback circuit is connected between the output terminal of the negative charge pump 101 and another input terminal of the AND gate 102, with the feedback circuit including a comparator 103, a resistor voltage-division circuit 104 and a positive-negative voltage conversion circuit 105. The resistor voltage-division circuit 104 in FIG. 1 is formed by a plurality of resistors interconnected in series, and the connection relation between the resistors can be regulated though the control of the digital signal Dac over the switch, thereby controlling the component-voltage proportion of the resistor voltage-division circuit 104. Because what is outputted by the resistor voltage-division circuit 104 is a component voltage of the negative voltage Vneg, the component voltage still needs to be converted into a positive voltage by the positive-negative voltage conversion circuit 105. The positive-negative voltage conversion circuit 105 outputs a positive component voltage value, which is compared with a reference voltage Vref, thereby outputting a feedback voltage, i.e. a clock enable signal Clock_en, which controls whether the clock signal Clock is provided to a circuit of the charge pump 101, thus regulating the output voltage Vneg of the charge pump 101 to an expected value.
It can be seen from FIG. 1 that the resistor voltage-division circuit 104 in an existing feedback circuit is formed by a plurality of resistors interconnected in series, and will occupy a larger area; besides, the component voltage outputted by the resistor voltage-division circuit 104 is negative, and needs to be converted into a positive voltage by the positive-negative voltage conversion circuit 105, which results in a slow feedback speed, with the waveform of the output negative voltage Vneg of the negative charge pump 101 not very good.